Spectacles having superimposed polarizing lenses are well known. U.S. Pat. No. 2,005,426 discloses sunglasses having two superimposed polarized lenses mounted in conventional spectacle frames. One of the two lenses is fixed in relation to the frame, while the other is rotatable in relation to the first lens. In this fashion, the pair of polarized lenses for each eye may be adjusted in relation to one another, thereby regulating the light transmission through the lens pair.
U.S. Pat No. 4,119,369 issued to Vaitok Eloranta and Benjamin Ruggles describes superimposed pairs of light polarizing elements, one pair of such elements being fixed and another pair being rotatable with respect to the fixed pair to provide variable light transmission. In this device, the lens pairs are superimposed in a single eyeglass frame, and the rotating lenses are interconnected by a tie bar to insure nearly identical axial rotation of the rotating elements.
U.S. Pat. Nos. 4,592,262 and 5,210,552 disclose pairs of polarized lens elements which are synchronized in rotation through a centrally mounted gear. Both of these devices comprise separate lens elements, one superimposed over the other.
Further, it is known that ophthalmic lenses may be designed incorporating fluids for the purposes of creating variable power lenses. See, for example, U.S. Pat. Nos. 4,913,536 and 5,124,734. The benefit of the application of this technology to superimposed polarizing lenses is the reduction of surface reflection and refraction resulting from the incidence of light on multiple surfaces in superimposed lenses.